The cellular slime molds undergo a period of vegetative growth during which a large population of independent-living amoebae are produced. Aggregation of the amoebae into pseudoplasmodia occurs in response to the chemotactic agent cyclic AMP. Following aggregation cell division begins to decline and cell contact results in the differentiation of the cells into two types, prestalks and prespores, which subsequently become the stalks and spores of the mature fruiting bodies. The proposed research involves the search for an 3H-labeled oligosaccharide sugar(s) which will bind to the cell surfaces of Dictyostelium discoideum amoebae. The incorporation of a sugar at specific stages of development may provide clues in the role of oligosaccharides in cell adhesion and interactions. L-fucose has been shown to be specifically incorporated into prespore cells but not into prestalk cells. A sugar which specifically labels prestalk cells will be sought. These probes will be used to determine the pattern of prespore and prestalk cell differentiation during pseudoplasmodium formation in several Dictyostelium species. Experiments will be conducted which elucidate the role of cell interaction in oligosaccharide sugar incorporation and synthesis. The incorporation of 3H-labeled sugar will be monitored by autoradiography.